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ECOL111 EXAM Questions and Correct
Answers
Evapotranspiration Ans: The process by which water moves from
the earth to the atmosphere by evaporation and transpiration from
plants.
Aridity Index (AI) Ans: The ratio of precipitation and potential
evapotranspiration (AI = precipitation/potential
evapotranspiration). The smaller the number, the greater the
aridity.
Why are drylands important for carbon storage? Ans: They are
extensive, stable, and able to sequester large amounts of carbon
for a long time.
What are the four major constituents of water potential? Ans:
Osmotic potential, turgor potential, gravitational potential, metric
potential.
Osmotic Potential Ans: Energy associated with dissolved solutes -
salt water has a lower potential than fresh water.
Turgor Potential Ans: Energy associated with the exertion of
pressure - water moves from high pressure to low pressure.
Gravitational Potential Ans: Energy associated with gravity - water
flows downslope.
Matric Potential Ans: Energy associated with attractive forces
between molecules - e.g surface tension, capillary action, soil-
bound water.
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, 2 | Page
Niche differentiation Ans: Differentiation in multiple niche
dimensions is what allows species to coexist given competitive
exclusion.
Competitive exclusion Ans: If two species occupy the same niche,
one will be better at exploiting the most limiting resource and
eventually exclude the other.
Water potential Ans: the potential energy of water per unit volume
relative to pure water.
Hydrological niche example Ans: Cape Flora, SA. Water availability
for plants is linked to soil drainage as well as bioclimatic factors.
Plant family Restionacaeae Ans: Close link between precipitation
and species distribution.
Facilitation Ans: The balance between the positive and negative
effects in close proximity determines net outcome of species
interactions.
Facilitation in the drylands - example Ans: Nurse Plants - fertile
area under the Nurse Plant allows smaller low to the ground plants
to survive.
Why do animals have more potential for water loss than plants?
Ans: Physiology - animals have specialised organs for gas
exchange, ingestion and digestion, circulation and excretion.
Resistance Ans: A force that impedes water movement. Barriers to
water movement include skin and waxy cuticles. The highest
resistance is found in terrestrial arthropods.
© 2025 All rights reserved
ECOL111 EXAM Questions and Correct
Answers
Evapotranspiration Ans: The process by which water moves from
the earth to the atmosphere by evaporation and transpiration from
plants.
Aridity Index (AI) Ans: The ratio of precipitation and potential
evapotranspiration (AI = precipitation/potential
evapotranspiration). The smaller the number, the greater the
aridity.
Why are drylands important for carbon storage? Ans: They are
extensive, stable, and able to sequester large amounts of carbon
for a long time.
What are the four major constituents of water potential? Ans:
Osmotic potential, turgor potential, gravitational potential, metric
potential.
Osmotic Potential Ans: Energy associated with dissolved solutes -
salt water has a lower potential than fresh water.
Turgor Potential Ans: Energy associated with the exertion of
pressure - water moves from high pressure to low pressure.
Gravitational Potential Ans: Energy associated with gravity - water
flows downslope.
Matric Potential Ans: Energy associated with attractive forces
between molecules - e.g surface tension, capillary action, soil-
bound water.
© 2025 All rights reserved
, 2 | Page
Niche differentiation Ans: Differentiation in multiple niche
dimensions is what allows species to coexist given competitive
exclusion.
Competitive exclusion Ans: If two species occupy the same niche,
one will be better at exploiting the most limiting resource and
eventually exclude the other.
Water potential Ans: the potential energy of water per unit volume
relative to pure water.
Hydrological niche example Ans: Cape Flora, SA. Water availability
for plants is linked to soil drainage as well as bioclimatic factors.
Plant family Restionacaeae Ans: Close link between precipitation
and species distribution.
Facilitation Ans: The balance between the positive and negative
effects in close proximity determines net outcome of species
interactions.
Facilitation in the drylands - example Ans: Nurse Plants - fertile
area under the Nurse Plant allows smaller low to the ground plants
to survive.
Why do animals have more potential for water loss than plants?
Ans: Physiology - animals have specialised organs for gas
exchange, ingestion and digestion, circulation and excretion.
Resistance Ans: A force that impedes water movement. Barriers to
water movement include skin and waxy cuticles. The highest
resistance is found in terrestrial arthropods.
© 2025 All rights reserved
